powerpc is a bid of an oddball here. It seems to have CONFIG_HIGHPTEbehavior at all times when compiled as 32-bit. There's even an#ifdef CONFIG_HIGHPTE in arch/powerpc/mm/pgtable_32.c, but there's notrace of HIGHPTE in Kconfig anywhere.

This gives ppc32 an explicit HIGHPTE in Kconfig so that we can usethe #ifdef in asm-generic/ptemap.h and let ppc use the generic codewith x86 and frv.

It also removes the HIGHPTE #ifdef on ppc32 since it will be onunconditionally.